With rapid development of touch sensing technology, many electronic apparatuses such as mobile phones, notebook computers or tablet computers take advantage of touch devices to provide intuitive operation and easy human-machine interface. These electronic apparatuses hugely enter modern lives and great business opportunities are created. There are two known touch sensing technologies, i.e. capacitive sensing and resistive sensing.
For capacitive sensing, when the touch device is touched with a human finger or a conductive object, a capacitor is temporarily formed on the electrode corresponding to the touched position. Therefore, equivalent capacitance of the corresponding electrode changes. A sensor circuit can determine the touched position on the touch device according to the equivalent capacitance change of the corresponding electrode.
For resistive sensing, when an object such a human finger or a stylus presses down onto a surface of the touch device, the upper electrode and the lower electrode are electrically connected at the pressed position so that the electrodes behave as a voltage divider circuit. Therefore, the sensor circuit can determine the pressed position on the touch device according to the voltage change of the upper electrode and the lower electrode.
Since large-area flat-panel display gains popularity now and touch sensing technology is widely used as the most friendly human-machine interface, there is an increased demand for large-area touch screen these days. For a large-area flat-panel display, optimum viewing distance increases. It does not make sense to control the display by actually touch a surface of the display with a finger or a conductive object instead of remote control. Therefore, a novel touch sensing method and touch device are desired.